Emerson 20/20 service manual Digital Outputs

Section 18 • Auxiliary Input / Output

Inhibit Check:

•Selecting this checkbox enables the inhibit function of the Vission 20/20 for the desired digital input. An inhibit check prevents the compressor from starting if the condition is true where a trip will shut down the compressor after it as started. The inhibit can be selected to inhibit on a high or low input and can be selected to work with or without the alarm and trip function

Digital Outputs

The digital outputs section of the Auxiliary I/O screen al- lows an operator to configure the auxiliary digital out- puts. The digital output can be configured to activate (go High, 120vac) based on either a digital input or a specified level on an analog input. Every digital and ana- log input in the Vission 20/20 are made available for con- trolling a digital output.

Analog Input:

•Selecting the Analog Input radio button fills the Active Input drop-down box with all available analog inputs. One of the analog inputs can then be selected to control the digital outputs.

Digital Input:

•Selecting the Digital Input radio button fills the Active Input drop-down box with all available digital inputs. One of the digital inputs can then be selected to control the digital outputs.

Run Always:

•Selecting this checkbox enables the function that controls the digital output to operate only when the compressor is running or runs all the time.

Analog Trigger:

•The analog trigger toggles the digital output based on a specified value plus the specified differential value.

•Analog Trigger value:

•This defines the specified value in which the output will toggle. This is an absolute value and not based on units. For example, 100 could mean temperature or pressure depending on the type of input selected.

•N/O & N/C:

•Choosing the Normally Open (N/O) or Normally Closed (N/C) radio buttons defines what the output will be above or below the trig- ger value. In the N/O setting, the output will be

off (0vac) while the input value is below the trig- ger value.

•Differential:

•This is the differential around the trigger val- ue. For example, if a trigger value of 100 is en- tered with a differential of 1, then as the value increases to 101, the output will be triggered. If the value decreases to 99, then the output will be toggled in the opposite direction.

Digital Relay:

•The digital relay option is used to pass along the in- formation from a digital input to another control de- vice or to operate a peripheral device. This output can be configured to either reflect the selected input or show the opposite value.

•Mirror:

•Selecting this option will produce a high out- put when the selected input is High; and pro- duce a low output when the selected input is low.

•Invert:

•Selecting this option will produce a low out- put when the selected input is high; and pro- duce a High output when the selected input is low.

Analog Inputs

The Analog inputs section of the auxiliary I/O screen al- lows an operator to define the function of an instrument connected to the Vission 20/20. The analog inputs can be configured to simply monitor an input for informa- tional purposes or used as a control input for the auxil- iary digital and analog outputs. The analog inputs can also be configured to alarm, trip, and inhibit on specified values.

•Alarm / Trip:

•This drop-down box allows the operator to select whether the analog input should gener- ate an alarm, trip, or both when the input value exceeds the limits entered into the alarm and trip entry boxes.

•Inhibit:

•Selecting this checkbox will prevent a start if the input value exceeds the alarm limit values.

•Low Alarm:

•This defines the lower limit of the input value that when exceeded will generate an alarm.

18 – 2 Vission 20/20 • Operation and Service Manual •Vilter/Emerson • 35391SC 1.8.5153